It has recently become common for management of hotels, theaters and other public gathering places to incorporate some type of lighted direction system in their hall and room carpets so that, in case of fire or other emergency, the light system can be intermittently lighted to direct guests to a safe exit. The lights may assume the pattern of arrows or sequentially flashing lights or a number of other configurations. Normally, the illumination system includes a flat, multi-wire cable installed beneath the carpet. Small lamps are connected to this cable. Either the lamps themselves or associated electric leads pass through holes in the carpet.
Several types of multi-cable assemblies exist. One type includes closely bunched wires. Another type includes parallel, closely spaced flat copper conductors laminated between two multiply plastic sheets. A third type, described in the above-referenced U.S. Pat. application No. 899,494, features a lamination of a plurality of flat, tinned copper strip conductors, laminated between a pair of organic plastic insulating sheets, which sheets adhere tightly to each other but at least one of which does not adhere to the copper strip conductors. Power is supplied to each of the conductors and the light bulbs are arranged in any desired pattern, receiving power from the conductors.
A number of configurations for providing and distributing the power to the lamps have been proposed. In one configuration, one of the conductors includes a plurality of electrically isolated portions each of which is electrically connected to a respective one of the other conductors. The light bulbs are placed along the segmented conductor, one lead connected to a conductor segment, the other connected to a common bus conductor, and a switching mechanism controls the sequence of lighting by selectively providing power to the other conductors.
The connections between the segmented conductor and the others may be either by a simple wire or may be by a portion of the segmented conductor itself, which has been cut from the remaining length, folded back upon itself and at right angles to the major portion of the conductor, so that it crosses neighboring conductors to join the desired second conductor. Of course, insulation must be provided to prevent electrical contact between the folded connecting conductor and the underlying conductors. It is possible to utilize the adhered plastic laminated sheet for this purpose.
In another scheme, the cross connections may be provided by a plurality of conductor connecting patterns carried on one of the plastic insulating sheets, typically printed thereon using a conductive graphite, nickel or silver ink. An electrical resistance heater, using conductive patterns printed on insulating sheets is disclosed in co-assigned U.S. Pat. No. 4,485,297, issued on Nov. 27, 1985, which is incorporated herein by reference.
Known lamp and lens assemblies for use with flat, multi-wire cables under carpets have drawbacks. A typical assembly includes a lamp fixture and a light-emitting diode or a small light bulb with a protective plastic cover. These are fragile. The bulbs or diodes are in a place where they receive constant abuse from marching pedestrians. The hard plastic case of the bulb, and the bulb itself, may break. Further, during installation, relatively large holes must be cut in the carpet so that the plastic cover may protrude and provide illumination. Finally, the covers are always visible and detract from the aesthetic effect of most carpets. This provides a constant and unpleasant reminder to the guests that hazards sometimes arise.